Levels of tweeting vary wildly between cultures. Greeks are less likely to tweet with mobile smartphones than Spanish. This can be in part accounted for by income. But also do not forget that Greeks could quickly start tweeting in the way Arab have since the Arab Awakening.

A very key thing to remember is that Greeks don't need to tweet. Why, well here are some key observations:

Protests in Greece are more organized, they involve more established groups within civil society like trade unions. They have the ability to organize and communicate that pre-date twitter.

Protests in Greece contain a larger band of age demographics. Unlike Spain the Greek protests have drawn people from almost every demographic in the country. And unlike Egypt Greece is a European country with an older population. Therefore a large part of the demonstrations are people are not digital natives.

Protests have often been violent. Though there are debates of who started the fighting Greece protests have seen more confrontation. Tweeting is generally more active in large peaceful protests.